1. Field of the Invention
This invention concerns dielectric barrier discharge lamps that use dielectric barrier discharges to emit excimer light.
2. Description of Related Art
Recent years have seen the development and practical application of surface treatment technology in which metals, glass and other materials are irradiated with vacuum ultraviolet light at wavelengths of 200 nm or less, in which the action of the vacuum ultraviolet light irradiation heat treatment equipment and the ozone produced thereby affect the material being treated, including cleaning treatment technology that removes organic pollutants adhered to the surface of the material being treated, and oxide film formation technology that forms an oxide film on the surface of the material being treated.
The lamps used to conduct this sort of ultraviolet treatment have been dielectric barrier discharge lamps that have a discharge chamber made of a dielectric and filled with an appropriate gas for excimer light, in which a dielectric barrier discharge (also called an xe2x80x9cozonizer dischargexe2x80x9d or xe2x80x9csilent dischargexe2x80x9dxe2x80x94see Denki Gakkai: xe2x80x9cDischarge Handbook,xe2x80x9drev. ed. June 1989, p 263) in the discharge chamber produces excimers and causes the emission of excimer light.
An example of a method of producing such a dielectric barrier discharge lamp is described below. FIG. 7 is an explanatory cross-section showing an example of the structure of the chamber material to form the discharge chamber in a conventional dielectric barrier discharge lamp. In this figure, 40A is chamber material to form the discharge chamber of the dielectric barrier discharge lamp. It has a two-layer structure comprising a cylindrical outer tube 41 and an inner tube 42 made of quartz glass, which is a dielectric. The two ends of the outer tube 41 and the inner tube 42 are joined by end walls 43, 44, and the space between the outer tube 41 and the inner tube 42 forms a toroidal internal space R. Additionally, an exhaust tube 45 is attached to the end wall 43 so as to connect to the internal space R.
Before the internal space R is filled with a discharge gas, the interior of this chamber material 40A is cleaned, perhaps by inserting a needle 46A of a syringe 46 into the exhaust tube 45, as shown in FIG. 8, and injecting a cleaning reagent, such as an aqueous solution of ammonium fluoride, for example, into the chamber material 40A. Then, after the interior surface of the chamber material 40A has been cleaned, the cleaning reagent is shaken out of the chamber material 40A. After that, the chamber material 40A is rinsed with water to wash out any remaining cleaning reagent; the rinse water is injected and removed in the same way as the cleaning reagent was.
After the chamber material 40A with its clean inner surface is dried, the exhaust tube 45 is connected to exhaust equipment, the air in the internal space R is exhausted, and the internal space R is filled with the discharge gas. Then, as shown in FIG. 9, the exhaust tube 45 is burned off and the internal space R is sealed by means of a burner, for example, producing a lamp proper 50 that has discharge gas sealed into the discharge chamber 40 with an exhaust tube remnant 47.
The dielectric barrier discharge lamp is produced by using appropriate means to attach an electrode to the outer surface of the outer tube 41 of the lamp proper 50, and another electrode to the inner surface of the inner tube 42.
Nevertheless, there are the following problems when dielectric barrier discharge lamps are manufactured by the method described above. It is difficult to perform, with high work efficiency, the operations of injecting and removing the cleaning fluids into and out of the chamber material 40A through the exhaust tube 45 attached to the chamber material 40A. As a result, the manufacture of dielectric barrier discharge lamps requires a long time.
Moreover, because it is difficult to perform the operations of injecting and removing the cleaning fluids into and out off the chamber material 40A, there are times when the inner surface of the chamber material 40A cannot be cleaned adequately, and dirt or foreign objects remain inside the chamber material 40A. As a result, when a dielectric barrier discharge lamp is manufactured using that chamber material 40A, good discharges in that dielectric barrier discharge lamp will be obstructed, the lighting intensity will drop, and a lighting flaw will occur.
This invention is based on the situation described above, and has a primary object of providing a dielectric barrier discharge lamp of which the inner surface of the chamber material can be cleaned easily and reliably, which consequently has good lighting characteristics, and which is easy to manufacture.
This object is achieved by the invention by a dielectric barrier discharge lamp having a discharger chamber with a cylindrical, double-tube construction comprising an outer tube and an inner tube, in which the cylindrical discharge space formed between the outer tube and the inner tube is filled with a discharge gas in which excimer molecules are formed by a dielectric barrier discharge, and in the discharge chamber is formed with at least two fluid distribution tube remnants that connect to each discharge chamber.
It is preferable that the dielectric barrier discharge lamp described above have two or more fluid distribution tube remnants formed on opposite ends of the discharge chamber.
In the manufacture of the dielectric barrier discharge lamp constituted as described above, there are two or more fluid distribution tubes on the chamber material that makes up the discharge chamber, and so it will be possible, while using at least one fluid distribution tube as a route for injection or removal of cleaning fluids, to secure the other fluid distribution tube as a route for air in the chamber material to be discharged, and so the action of injecting cleaning fluids into the chamber material and the action of removing them can be performed easily and reliably. As a result, it is possible to clean and remove dirt and foreign objects from the inner surface of the chamber material. Thus, it is possible to prevent drops in lighting intensity and the occurrence of lighting flaws that originate from dirt or foreign objects on the inner surface of the chamber material, and so it is possible to obtain good lighting characteristics.